The present invention relates to a header plateless heat exchanger obtained by stacking flat tubes having both ends bulging, more specifically, relates to one in which flat tubes are each formed by joining a pair of grooved plates together, in which air-tightness and liquid-tightness of the joining portion are improved.
Header plateless heat exchangers are such that flat tubes 5 having both ends bulging in a thickness direction are stacked at the bulging portions to form a core (6), and no header plate is required, as illustrated in FIG. 13 (see also FIG. 1). In addition, a pair of header tanks (6) are disposed, at the both ends of the core (6) in the longitudinal direction, and a casing (7) is fitted over the outer periphery of the core (6).
The flat tubes 5, which serve as constituent elements of this core (6), have a joined body including a first plate (1) and a second plate (2), which is formed into a pair of groove shapes. The core (6) and the header tank (8) of such a heat exchanger need to be connected using brazing without any gap.
Related prior art includes Japanese Patent Laid-Open No. 2011-2133 and Japanese Patent Laid-Open No. 2011-232020.